Given the typical histopathology of baseline psoriasis, the grading system for the histological assessment of epidermal hyperplasia is: (1) not improved; (2) good improvement (reduction in hyperplasia and normalized differentiation, but most suprabasal keratinocytes still express K16); or (3) excellent improvement (reduction in hyperplasia, normalized differentiation, absent K16 expression or small foci of residual keratin expression). Here, KRT16 is linked to psoriasis.